The Cameron-brokered "deal" is that IDS can have the funds if he finds £3 billion from other benefit cuts - indeed Michael White reports that Osborne insists IDS must cut £5 for every £1 he wants to reinvest in the system - which sounds much more like a clear Treasury victory than a compromise. So universal benefits are back in the firing line, with those which David Cameron promised would be sacrosanct back under review.
So what about those tricky general election promises? Here are five ways to deal with the political headache.
1. Keep the pledges made at the election.
This "honesty option" would mean being constrained during this Parliament by the promises made in the campaign. You could announce plans to cut the benefits you pledged to protect - but could not introduce the cuts until the budget after the next General Election.
David Cameron's clear public commitments made in the election campaign were in the George Bush "Read my lips" category of clarity, with Cameron appearing to give himself no room at all.
Indeed, as Nick Robinson pointed out on May 5th, Cameron used the very same phrase as Bush on the eve of the General Election when promising to protect pensioner's benefits.
"You can read my lips. That is a promise from my heart."
"We have made a very clear commitment on that", said Cameron in the campaign when asked whether he would consider cutting the winter fuel payment. Having angrily accused his political opponents of scaremongering and "lies", how could he adopt the policy they argued he would consider?
2. Change the circumstances have changed since you made the pledge
The facts of the deficit were just as clear in April when these pledges were made - and then repeated in the Coalition agreement. That IDS' welfare reforms required up-front funding was also very clear, though his Centre for Social Justice was reticent when it came to costing the proposals ahead
The Coalition has already played its "risk of Greek default card" over and over again, particularly to justify its u-turn on VAT - where George Osborne told voters this would not be necessary, and the LibDems campaigned against the Tories over it. Its repeated use to justify serial pledge-breaking would be risible.
Politically, it will also give Cameron's opponents a free hand - "which pledges will they break this time" - at the next election, given that no Tory manifesto commitment could be considered solid. This ought to be a significant theme for media interviewers: 'if you broke your pledges last time, why should anybody believe you would keep these ones?'
3. Blame the Coalition - and say the LibDems pushed the Tories to the right
Coalitions can be a convenient pledge-ditching mechanism. ("Would you like this as well; we've been trying to get rid of it for some time" was Simon Hughes' paraphrase of the Tory negotiating team's approach to some of their own policies in the Nick Robinson documentary).
That is an accurate description of what happened to the Child Trust Fund, where the Tories would have restricted it but the LibDems won the argument for abolition.
On the Winter Fuel Payment, the LibDems wanted to raise the qualifying age to 65 (while promising to fund an extension for disabled pensioners with the savings). So the George Osborne could again adopt LibDem policy, saving around £600 million, while ditching his own leader's pledge.
But the two parties can not blame the need for Coalition compromise when both parties need to u-turn at once. And while Nick Clegg and Vince Cable have serially flipped and flopped over means-testing child benefit or maintaining their party's policy to keep it universal, both Clegg's LibDems and the Conservatives were very clear in their highest profile election interviews that they were not questioning the universality of child benefit.
Political observers may notice an "austerity asymetry" over which party gets to compromise. Where the Tory policy is to the right - as in the central, strategic choice of the Coalition for faster and deeper spending cuts, or over raising VAT - the LibDems have had to give way. But while the LibDems have been unable to prevail with their mansion tax, and had to compromise on equalising capital gains rates even after securing a Coalition commitment, they have found the Conservatives very happy to compromise where LibDem policy is for deeper cuts than the Tory manifesto.
4. Move the goalposts and claim to have kept the pledge
This can be legitimate or dodgy. George Osborne's decision to freeze child benefit for three years maintained the pledge not to means-test it, and was a better policy choice
But this can also become a clear exercise in political sophistry. Geoffrey Howe's VAT dodge in 1979 was a clear and recurring case.
Take this suggestion from the always well informed Paul Goodman about a possible swerve around Cameron's free bus pass pledge.
The emotional problem is that pensioners in particular believe that they've paid into the system for what they get back. That our welfare system doesn't work this way scarcely shakes their conviction – itself understandable – that their sacrifices deserve recognition. It was with this sensibility in mind that David Cameron pledged to keep free bus passes during the election. That promise wouldn't be inconsistent with raising the age at which one qualifies for a pass to as high as 75. If the deficit's to be eliminated, such decisions will have to be made.
The pledge "to keep free bus passes" has clearly been broken for those aged between 65 and 75. Under Goodman's logic, couldn't one raise the qualification age to 100 and claim to have kept the free bus pass?
Look out for many similar dodges - along with vehement claims the promises have not been broken. So how to tell the difference? Surely it is whether the reasonable, non-aligned voter will believe about the honesty of the claims. Will opinion polls show a majority believe the pledge has been kept or broken?
Attempts at dodges which fail that test may simply compound the broken promise with a further reputation for slipperiness and evasion. The classic case was the ill-fated Bush administration attempt to claim that agreeing "tax revenue increases" in the budget were not the same as "new taxes"; this only deepened the effect of the "Read my lips: I lied" headlines. If the pledge is being broken, it may be better to admit it.
5. Call a General Election to secure a mandate for your new policy
Given the centrality of the theory of the manifesto and the mandate in British politics, the British political convention is that a government wishing to reverse a significant manifesto commitment should seek a new electoral mandate.
Stanley Baldwin called a new election in 1923, just 13 months after the previous one had given the Tories a majority of 70, because he wanted to break the Tory manifesto commitment on free trade, to introduce tariff reform.
Baldwin did not get the mandate he sought in 1923, and had to give way to a minority Labour government. However, Baldwin's reputation for honesty and straight-dealing helped to make him the dominant figure in inter-war politics.
I think we can be quite sure that this is the one option which David Cameron will not be considering.
So which will it be?